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Fencer Intel
critical 9.6

CVE-2026-62863 json

MoLing: unauthenticated SSE and wildcard CORS expose tool sessions

published 4mo ago modified 5d ago also EUVD-2026-114460 , GHSA-qpgh-hp5g-4vwp

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository gojue/moling. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
9.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 24%
public exploits
0
none known

Summary

MoLing is a computer-use and browser-use based MCP server. Prior to 0.5.0, when MoLing runs in SSE mode using `-l`, its `/sse` and `/message` HTTP endpoints do not authenticate requests and the `mcp-go` dependency sets `Access-Control-Allow-Origin: *`. A malicious web page can open a cross-origin `EventSource` to `/sse`, including a loopback listener, and read the `endpoint` event to obtain `sessionId`. After a victim running SSE mode visits that page, the attacker can use the disclosed `sessionId` against `/message` to send unauthorized MCP tool calls. Depending on the configured tools, those calls can read or write local files, execute commands or perform other actions. Binding only to loopback does not prevent this browser-mediated attack. This issue is fixed in version 0.5.0.

Patch / fix

Is CVE-2026-62863 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
5d ago

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

Affected products

  • gojue moling

Classification

Weakness
  • CWE-942 Permissive Cross-domain Security Policy with Untrusted Domains
  • CWE-306 Missing Authentication for Critical Functionality

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of gojue/moling published their own advisory on GitHub. Reviewed sources take precedence over it.